LTC2901
Programmable Quad Supply
Monitor with Adjustable Reset
and Watchdog Timers
FEATURES
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DESCRIPTIO
Simultaneously Monitors Four Supplies
16 User Selectable Combinations of 5V, 3.3V, 3V,
2.5V, 1.8V, 1.5V and/or
±Adj
Voltage Thresholds
Guaranteed Threshold Accuracy:
±1.5%
of
Monitored Voltage Over Temperature
Selectable Supply Tolerance: 5% and 10% Below
Monitored Voltage (LTC2901-3/LTC2901-4)
Low Supply Current: 43μA Typ
Adjustable Reset Time
Adjustable Watchdog Time
Open-Drain RST Output (LTC2901-1/LTC2901-3)
Push-Pull RST Output (LTC2901-2/LTC2901-4)
Individual Nondelayed Monitor Output for Each Supply
Power Supply Glitch Immunity
Guaranteed RST for V
CC
≥
1V
16-Lead Narrow SSOP Package
The LTC
®
2901 is a programmable supply monitor for
systems with up to four supply voltages. One of 16 preset
or adjustable voltage monitor combinations can be se-
lected using an external resistor divider connected to the
program pin. The preset voltage thresholds are accurate
to
±1.5%
over temperature. All four voltage comparator
outputs are connected to separate pins for individual
supply monitoring.
The reset and watchdog delay times are adjustable using
external capacitors. Tight voltage threshold accuracy and
glitch immunity ensure reliable reset operation without
false triggering. The RST output is guaranteed to be in the
correct state for V
CC
down to 1V. The LTC2901-1/
LTC2901-3 features an open-drain RST output, while the
LTC2901-2/LTC2901-4 has a push-pull RST output.
The 43μA supply current makes the LTC2901 ideal for
power conscious systems and it may be configured to
monitor less than four inputs. The parts are available in
the 16-lead narrow SSOP package.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Patent Pending.
APPLICATIO S
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Desktop and Notebook Computers
Multivoltage Systems
Telecom Equipment
Portable Battery-Powered Equipment
Network Servers
TYPICAL APPLICATIO
5V
3.3V
DC/DC
CONVERTER
2.5V
1.8V
Quadruple Supply Monitor (5V, 3.3V, 2.5V, 1.8V)
SYSTEM
LOGIC
Quadruple Supply Monitor (5V, 3.3V, 2.5V, 1.8V)
10% Undervoltage Monitoring, Watchdog Asserts RST
5V
3.3V
DC/DC
CONVERTER
2.5V
1.8V
SYSTEM
LOGIC
V3
V1
V4
COMP1
R3
10k POWER
GOOD
V2
C1
0.1μF
C2
0.1μF
V
REF
R1
59k
1%
R2
40.2k
1%
COMP2
LTC2901-2
COMP3
COMP4
WDI
WDO
C1
0.1μF
C2
0.1μF
V
PG
GND CRT
C
RT
47nF
RST
CWT
C
WT
47nF
2901 TA01
R1
59k
1%
R2
40.2k
1%
t
RST
= 216ms
t
WD
= 940ms
U
V3
V1
V4
COMP1
COMP2
LTC2901-4
COMP3
COMP4
V
REF
WDI
TOL
V
PG
GND CRT
C
RT
47nF
RST
CWT
C
WT
47nF
t
RST
= 216ms
t
WD
= 940ms
5V
2901 TA01b
U
U
R3
10k POWER
GOOD
V2
2901fb
1
LTC2901
ABSOLUTE
AXI U
RATI GS
V1, V2, V3, V4, V
PG
..................................... – 0.3V to 7V
RST (LTC2901-1/LTC2901-3) ..................... – 0.3V to 7V
RST (LTC2901-2/LTC2901-4) ....... – 0.3V to (V2 + 0.3V)
COMPX ....................................................... – 0.3V to 7V
CWT, WDI, WDO ......................................... – 0.3V to 7V
V
REF
, CRT, TOL ............................ – 0.3V to (V
CC
+ 0.3V)
Reference Load Current (I
VREF
) ............................
±1mA
V4 Input Current (–ADJ Mode) ............................. –1mA
PACKAGE/ORDER I FOR ATIO
TOP VIEW
COMP3
COMP1
V3
V1
CRT
RST
WDO
WDI
1
2
3
4
5
6
7
8
16 COMP2
15 COMP4
14 V2
13 V4
12 V
REF
11 V
PG
10 GND
9
CWT
ORDER PART
NUMBER
COMP3
1
2
3
4
5
6
7
8
LTC2901-1CGN
LTC2901-2CGN
LTC2901-1IGN
LTC2901-2IGN
GN16 PART MARKING
29011
29012
29011I
29012I
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 110°C/W
Order Options
Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Lead Free Part Marking:
http://www.linear.com/leadfree/
ELECTRICAL CHARACTERISTICS
SYMBOL
V
RT50
V
RT33
V
RT30
V
RT25
V
RT18
V
RT15
V
RTA
V
RTAN
V
CC
PARAMETER
5V, 5% Reset Threshold
5V, 10% Reset Threshold
3.3V, 5% Reset Threshold
3.3V, 10% Reset Threshold
3V, 5% Reset Threshold
3V, 10% Reset Threshold
2.5V, 5% Reset Threshold
2.5V, 10% Reset Threshold
1.8V, 5% Reset Threshold
1.8V, 10% Reset Threshold
1.5V, 5% Reset Threshold
1.5V, 10% Reset Threshold
ADJ, 5% Reset Threshold
ADJ, 10% Reset Threshold
– ADJ Reset Threshold
Minimum Internal Operating Voltage
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, unless otherwise noted. (Notes 3, 4)
CONDITIONS
V1 Input Threshold
V1, V2 Input Threshold
V2 Input Threshold
V2, V3 Input Threshold
V3, V4 Input Threshold
V3, V4 Input Threshold
V3, V4 Input Threshold
V4 Input Threshold
RST, COMPX in Correct Logic State;
V
CC
Rising Prior to Program
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
2
U
U
W
W W
U
W
(Notes 1, 2, 3)
Operating Temperature Range
LTC2901-1C/LTC2901-2C/
LTC2901-3C/LTC2901-4C ....................... 0°C to 70°C
LTC2901-1I/LTC2901-2I/
LTC2901-3I/LTC2901-4I .................... –40°C to 85°C
Storage Temperature Range .................. – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................... 300°C
TOP VIEW
16 COMP2
15 COMP4
14 V2
13 V4
12 V
REF
11 V
PG
10 GND
9
CWT
ORDER PART
NUMBER
LTC2901-3CGN
LTC2901-4CGN
LTC2901-3IGN
LTC2901-4IGN
GN16 PART MARKING
29013
29014
29013I
29014I
COMP1
V3
V1
CRT
RST
TOL
WDI
GN PACKAGE
16-LEAD PLASTIC SSOP
T
JMAX
= 125°C,
θ
JA
= 110°C/W
MIN
4.600
4.350
3.036
2.871
2.760
2.610
2.300
2.175
1.656
1.566
1.380
1.305
0.492
0.466
– 18
TYP
4.675
4.425
3.086
2.921
2.805
2.655
2.338
2.213
1.683
1.593
1.403
1.328
0.500
0.473
0
MAX
4.750
4.500
3.135
2.970
2.850
2.700
2.375
2.250
1.710
1.620
1.425
1.350
0.508
0.481
18
1
UNITS
V
V
V
V
V
V
V
V
V
V
V
V
V
V
mV
V
2901fb
LTC2901
ELECTRICAL CHARACTERISTICS
SYMBOL
V
CCMINP
V
CCMINC
V
REF
PARAMETER
Minimum Required for Programming
Minimum Required for Comparators
Reference Voltage
The
●
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 5V, unless otherwise noted. (Notes 3, 4)
CONDITIONS
V
CC
Rising
V
CC
Falling
V
CC
≥
2.3V, I
VREF
=
±1mA,
C
REF
≤
1000pF
T0L Low
T0L High
V
CC
≥
V
CCMINP
V
PG
= V
REF
V1 = 5V, I
VREF
= 12μA, (Note 5)
V2 = 3.3V
V3 = 2.5V
V3 = 0.55V (ADJ Mode)
V4 = 1.8V
V4 = 0.55V (ADJ Mode)
V4 = –0.05V (–ADJ Mode)
V
CRT
= 0V
V
CRT
= 1.3V
C
RT
= 1500pF
V
X
Less Than Reset Threshold V
RTX
by More Than 1%
I
SINK
= 2.5mA; V1 = 3V, V2 = 3V;
V3, V4 = 0V; V
PG
= 0V
I
SINK
= 100μA; V2 = 1V; V1, V3, V4 = 0V
I
SINK
= 100μA; V1 = 1V; V2, V3, V4 = 0V
I
SOURCE
= 1μA
I
SINK
= 2.5mA; V1 = 5V, V2 = 3.3V;
V3, V4 = 1V; V
PG
= 0V
I
SOURCE
= 200μA
V
CWT
= 0V
V
CWT
= 1.3V
C
WT
= 1500pF
V
CC
= 3.3V to 5.5V
V
CC
= 3.3V to 5.5V
V
CC
= 3.3V
V
WDI
= 0V
V
CC
= 3.3V to 5.5V
V
CC
= 3.3V to 5.5V
TOL = V
CC
MIN
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
TYP
MAX
2.42
2.32
1.228
1.163
V
REF
±20
75
2
1.2
15
0.8
15
15
–2.6
30
9
UNITS
V
V
V
V
V
nA
μA
μA
μA
nA
μA
nA
nA
μA
μA
ms
μs
V
V
V
V
V
V
V
PG
I
VPG
I
V1
I
V2
I
V3
I
V4
Programming Voltage Range
V
PG
Input Current
V1 Input Current
V2 Input Current
V3 Input Current
V4 Input Current
1.192
1.128
0
1.210
1.146
43
0.8
0.52
–15
0.34
–15
–15
–1.4
10
5
I
CRT(UP)
I
CRT(DN)
t
RST
t
UV
V
OL
CRT Pull-Up Current
CRT Pull-Down Current
Reset Time-Out Period
V
X
Undervoltage Detect to RST or COMPX
Output Voltage Low RST, COMPX
–2
20
7
150
0.15
0.05
0.05
●
●
●
●
●
●
●
●
●
●
●
●
0.4
0.3
0.3
V
OH
V
OL
V
OH
Output Voltage High RST, WDO, COMPX
(Note 6)
Output Voltage Low WDO
V2 – 1
0.15
0.8 • V2
–1.4
10
20
0.4
150
–10
–2
20
30
–2.6
30
40
1.6
0.4
Output Voltage High RST
(LTC2901-2/LTC2901-4) (Note 7)
I
CWT(UP)
CWT Pull-Up Current
I
CWT(DN)
CWT Pull-Down Current
t
WD
Watchdog Time-Out Period
V
IH
WDI Input Threshold High
V
IL
WDI Input Threshold Low
t
WP
WDI Input Pulse Width
I
WDI
WDI Pull-Up Current
Digital Input T0L
V
IL
T0L Low Level Input Voltage
V
IH
T0L High Level Input Voltage
I
INTOL
T0L Input Current
μA
μA
ms
V
V
ns
μA
V
V
μA
●
●
●
0.3V
CC
0.7V
CC
±0.1
±1
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings may
cause permanent damage to the device. Exposure to any Absolute Maximum
Rating condition for extended periods may affect device reliability and
lifetime.
Note 2:
All currents into pins are positive, all voltages are referenced to GND
unless otherwise noted.
Note 3:
The greater of V1, V2 is the internal supply voltage (V
CC
).
Note 4:
10% thresholds apply to the LTC2901-3/LTC2901-4 only when the
TOL pin is set to a logic high.
Note 5:
Under static no-fault conditions, V1 will necessarily supply quiescent
current. If at any time V2 is larger than V1, V2 must be capable of supplying
the quiescent current, programming (transient) current and reference load
current.
Note 6:
The output pins RST, WDO and COMPX have internal pull-ups to V2
of typically 6μA. However, external pull-up resistors may be used when faster
rise times are required or for V
OH
voltages greater than V2.
Note 7:
The push-pull RST output pin on the LTC2901-2/LTC2901-4 is
actively
pulled up to V2.
2901fb
3
LTC2901
TEST CIRCUITS
V1
V2
V3
V4
RST, WDO
LTC2901-1 OR COMPX
LTC2901-3
I
SOURCE
1μA
V1
V2
V3
V4
LTC2901-1
LTC2901-3
RST, WDO
OR COMPX
I
SINK
2.5mA,
100μA
V1
V2
V3
V4
LTC2901-2 RST
LTC2901-4
I
SOURCE
200μA
2901 F01
2901 F02
2901 F03
Figure 1. RST, WDO, COMPX V
OH
Test
Figure 2. RST, WDO, COMPX V
OL
Test
Figure 3. Active Pull-Up RST V
OH
Test
TI I G DIAGRA S
V
X
Monitor Timing
RST
WDI
t
WP
WDO
t
WD
t
WD
2901 TD2
RST
t
WP
WDI
2901 TD3
4
W
UW
V
X
V
RTX
t
UV
t
RST
1.5V
RST
2901 TD
COMPX
Watchdog Timing (LTC2901-1/LTC2901-2)
t
RST
Watchdog Timing (LTC2901-3/LTC2901-4)
t
RST
t
WD
t
RST
2901fb
LTC2901
TYPICAL PERFOR A CE CHARACTERISTICS
5V Threshold Voltage
vs Temperature
4.750
THRESHOLD VOLTAGE, V
RT33
(V)
THESHOLD VOLTAGE, V
RT50
(V)
4.725
4.700
4.675
4.650
4.625
4.600
20 40 60
–60 –40 –20 0
TEMPERATURE (°C)
3.115
3.105
3.095
3.085
3.075
3.065
3.055
3.045
THRESHOLD VOLTAGE, V
RT30
(V)
2.5V Threshold Voltage
vs Temperature
2.3750
2.3675
THRESHOLD VOLTAGE, V
RT25
(V)
THRESHOLD VOLTAGE, V
RT18
(V)
1.710
1.705
1.700
1.695
1.690
1.685
1.680
1.675
1.670
1.665
1.660
2.3600
2.3525
2.3450
2.3375
2.3300
2.3225
2.3150
2.3075
2.3000
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
THRESHOLD VOLTAGE, V
RT15
(V)
ADJ Threshold Voltage
vs Temperature
0.508
0.018
0.506
0.504
0.502
0.500
0.498
0.496
0.494
0.492
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
THRESHOLD VOLTAGE, V
RTAN
(V)
THRESHOLD VOLTAGE, V
RTA
(V)
0
–0.006
–0.012
–0.018
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
V
REF
(V)
U W
3.3V Threshold Voltage
vs Temperature
3.135
3.125
2.850
2.840
2.830
2.820
2.810
2.800
2.790
2.780
2.770
80
100
3V Threshold Voltage
vs Temperature
80 100
2901 G01
3.035
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
2.760
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
2901 G02
2901 G03
1.8V Threshold Voltage
vs Temperature
1.425
1.420
1.415
1.410
1.405
1.400
1.395
1.390
1.385
80
100
1.5V Threshold Voltage
vs Temperature
1.655
–60 –40 –20 0
20 40 60
TEMPERATURE (°C)
1.380
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
2901 G04
2901 G05
2901 G06
– ADJ Threshold Voltage
vs Temperature
1.228
1.222
1.216
1.210
1.204
1.198
V
REF
vs Temperature
0.012
0.006
80
100
1.192
– 60 –40 – 20 0 20 40 60
TEMPERATURE (°C)
80
100
2901 G07
2901 G08
2901 G23
2901fb
5
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